Method of making a dunnage platform

ABSTRACT

A dunnage platform is in the general shape of a rectangular slab with legs extending form one side. The dunnage platform is made from an expanded polystyrene core. A chemical combination process is used to chemically combine portion of the core proximal to its surface with high impact polystyrene. In a first of two parts of the combination process, the core is placed in a forming mold with one of its two sides and two thirds of its thickness extending therefrom. A heated sheet of high impact polystyrene is brought into contact with the portion of the core extending from the mold. In a similar manner, the other of the two sides of the core is made to extend from the forming mold for contact with a heated sheet of high impact polystyrene.

CLAIM OF PRIORITY

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 12/464,283, filed May 12, 2009, which applicationis a continuation of U.S. patent application Ser. No. 11/617,578, filedDec. 28, 2006 which issued as U.S. Pat. No. 7,544,262 on Jun. 9, 2009,which application is a continuation of U.S. patent application Ser. No.11/490,372, filed Jul. 20, 2006 which issued as U.S. Pat. No. 7,611,596on Nov. 3, 2009, which application is a continuation of U.S. patentapplication Ser. No. 10/921,903, filed Aug. 20, 2004 which issued asU.S. Pat. No. 7,128,797 on Oct. 31, 2006, which application is adivisional of U.S. patent application Ser. No. 10/166,988, filed Jun.11, 2002, and which issued as U.S. Pat. No. 6,786,992 on Sep. 7, 2004.The above applications and patents are herein expressly incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is in the general field of load-bearing structures and,more particularly, is a load bearing structure made from an expandedpolystyrene core that is chemically combined with high impactpolystyrene.

2. Description of the Prior Art

A shipping pallet is a well known load-bearing, moveable platformwhereon articles are placed for shipment. The pallet usually is loadedwith a multiplicity of items, such as cartons or boxes. The loadedpallet is movable with either a pallet truck or a forklift

There is a nine billion dollar market for pallets in the United States.There is a thirty billion dollar world wide market. Approximately ninetypercent of these markets is for pallets made from wood.

The weight of the wood pallet is in a range of forty to seventy pounds.Therefore, the weight of a cargo shipped on the wood pallet is reducedby from forty to seventy pounds to provide for the weight of the woodpallet.

It should be understood that injuries caused by wood splinters and nailsare frequent occurrences among people who handle the wood pallet.Additionally, disposal of the wood pallet at the end of its useful lifeis a threat to the environment.

There has been concern among nations about the use of the wood palletcausing an import of wood-boring insects, including the Asian LonghornedBeetle, the Asian Cerambycid Beetle, the Pine Wood Nematode, the PineWilt Nematode and the Anoplophora Glapripwnnis. Exemplary of damagecaused by imported insects is the fate of the Chestnut Tree in theUnited States. There was a time when it was said that a squirrel couldcross the United States on Chestnut Tree limbs without ever touching theground. Insect infestation has caused the extinction of the ChestnutTree in the United States.

Therefore, the wood pallet's weight, the injuries that it causes, itsthreat to the environment and the possibility of it causing animportation of wood-boring insects militates against the use of the woodpallet. As explained hereinafter, there is an attractive alternative tothe wood pallet.

SUMMARY OF THE INVENTION

An object of the invention is an easily movable load bearing structurethat is not likely to carry wood-boring insects.

Another object of the invention is a movable load bearing structure thatdoes not have splinters and nails that may cause injury.

According to the present invention, a dunnage platform has an expandedpolystyrene core with a region proximal to its surface that ischemically combined with a high impact polystyrene.

Because of a chemical combination of components, comparing the corebefore the chemical combination to the dunnage platform that is formed,there is an increase in strength to weight ratio of as much as 1000:1that allows the dunnage platform to carry loads comparable to loadscarried by a wooden pallet. The dunnage platform does not support insectlife and does not have splinters and nails that cause injury.

Other objects, features and advantages of the invention should beapparent from the following description of a preferred embodimentthereof as illustrated in the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a top side of a core of a dunnageplatform that is in accordance with the invention;

FIG. 2 is a perspective view of a bottom side of the core of FIG. 1;

FIG. 3 is a perspective view of a forming mold;

FIG. 4 is a side elevation of the core of FIG. 1 within the forming moldof FIG. 3 positioned below a clamping frame with a first high impactpolystyrene sheet clamped therein in preparation for a first of twoparts of a chemical combination process;

FIG. 5 is a perspective view of the clamping frame and the first sheetof FIG. 4;

FIG. 5A is a plan view of the first sheet of FIG. 3;

FIG. 5B is a view of FIG. 5 taken along the line 5B-5B;

FIG. 6 is a side elevation of the core of within the forming mold ofFIG. 3 positioned below the clamping frame after the first sheet hasbeen heated;

FIG. 7 is a side elevation of the clamping frame seated upon a marginalportion of the bottom side of the core;

FIG. 8 is a perspective view of the bottom side wherein holes have beendrilled through strengthened polystyrene;

FIG. 9 is a side elevation of the core within the forming moldpositioned below the clamping frame with a second high impactpolystyrene sheet clamped therein in preparation for the second part ofthe chemical combination process;

FIG. 10 is a side elevation of the core within the forming moldpositioned below the clamping frame after the second sheet has beenheated; and

FIG. 11 is a side elevation of the clamping frame of FIG. 10 seated upona marginal portion of the top side of the core.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIGS. 1 and 2, an expanded polystyrene core 10 is in thegeneral shape of a rectangular slab with an edge 12 (FIG. 1) that has awidth 14 which is approximately 1¾ inches. The core 10 has a smoothtopside 16 that is on the order of forty eight inches long and fortyinches wide. A bottom side 18 (FIG. 2) of the core 10 includes legs20-28 approximately four inches long extending therefrom.

The edge 12 is proximal to ma spaces 42, 44, 46, 48 on the bottom side18. The marginal spaces 42, 44, 46, 48 separate the legs 26-28, the legs20, 2326, the legs 20-22 and the legs 22, 25, 28, respectively, from theedge 12.

Because the core 10 is made from expanded polystyrene, it does not havesufficient structural strength to be useable as a load bearing platform.A dunnage platform with sufficient strength is formed by chemicallycombining a region of the core 10, proximal to its surface, with a highimpact polystyrene. Expanded polystyrene and high impact polystyrene arewell known. The dunnage platform described hereinafter has substantiallythe same dimensions as the core 10.

A first of two parts of a chemical combination process causes portionsof the expanded polystyrene proximal to the bottom side 18 to bechemically combined with the high impact polystyrene to formstrengthened polystyrene. Additionally, a portion of the expandedpolystyrene that is proximal to the edge 12 and in a proximalrelationship to the bottom side 18 is chemically combined with the highimpact polystyrene to form the strengthened polystyrene.

As shown in FIG. 3, a forming mold 50 has rectangularly disposed walls52-55 that define an interior 56 and a top surface 58. An interiorsurface 56U of the walls 52-55 outline a portion of the interior 56 thatis complimentary to a shape of the core 10 outlined by the edge 12.

An interior of the walls 52-55 form a shelf 60 that extends around theinterior 56. The shelf 60 has a surface 62 that is parallel to thesurface 58. For reason's explained hereinafter, a displacement betweenthe surfaces 58, 62 is less than one half of the width 14 (FIG. 1). Inthis embodiment, the displacement between the surfaces 58, 62 is onethird of the width 14.

As shown in FIG. 4, the mold 50 is moveable in a direction of the arrows63. The core 10 is retained within the mold 50 with a marginal portionof the top side 16 that is proximal to the edge 12 is seated upon thesurface 62 (FIG. 3) whereby the top side 16 is maintained within themold 50. Since the distance between the surfaces 58, 62 is one third ofthe width 14, two thirds of the edge 12 extends from the mold 50.Additionally, the bottom side 18 extends from the mold 50.

A fixedly positioned clamping frame 64 has a first high impactpolystyrene sheet 67 clamped therein. A heater 68 is positioned proximalto the frame 64.

As shown in FIG. 5, the frame 64 is made from an upper rectangular frame74 and a lower rectangular frame 76 that are held together by aplurality of screws 78. The length and width of the upper frame 74 issubstantially equal to the length and width, respectively, of the lowerframe 76.

As shown in FIGS. 5A, and 5B, with the screws 78 not tightened, edges ofthe sheet 67 (FIG. 5A) are inserted between the frames 74, 76 (FIG. 5B)in much the same way that edges of a bed sheet are inserted between amattress and a box spring. At corners of the frames 74, 76, the sheet 67is folded in much the same way that edges of the bed sheet are folded toform what is known as a hospital corner and inserted between the frames74, 76. When the edges and corners of the sheet 67 are inserted, thesheet 67 extends in a plane that causes it to cover a side 80 of theframe 76. Thereafter, the screws 78 are tightened whereby the sheet 67is fixedly maintained in the frame 64.

As shown in FIG. 6, in the first part of the process, the heater 68heats the sheet 67 to a temperature in a range of 293.degree. F. to375.degree. F. In response to being heated, the sheet 67characteristically sags. After the sheet 67 is heated, the heater 68 isremoved and the mold 50 is moved in a direction of the arrows 63.

It should be understood that when the sheet 67 is heated, it becomesfragile. Because the frame 64 is fixedly positioned, a risk of damage tothe sheet 67 is minimized.

As shown in FIG. 7, the mold 50 is moved until a portion of the heatedsheet 67 that covers the side 80 (FIG. 5B) is seated upon the surface 58(FIG. 3). The mold 50 is connected to a vacuum pump 84 through an airbox 86 and a connector line 88.

It should be understood that the core 10 is porous. When the vacuum pump84 operates, air may pass through the core 10, from the top side 16, tothe pump 84. The heated sheet 67 is not porous, thereby causing oneatmosphere of air pressure that draws the heated sheet 67 onto thebottom side 18 and the two thirds of the edge 12 that extends from themold 50.

The expanded polystyrene proximal to the bottom side 18 and proximal tothe two thirds of the edge 12 that extend above the mold 50 chemicallycombine with the high impact polystyrene of the sheet 67 to form thestrengthened polystyrene. The strengthened polystyrene is not porous.The side 18 and the legs 20-28 with the strengthened polystyreneproximal to their surface are hereinafter referred to as a side 18C withlegs 20C-28C, respectively.

As shown in FIG. 8, because the strengthened polystyrene is not porous,a plurality of holes 90 are drilled into the side 18C to approximate theporosity of expanded polystyrene.

As shown in FIG. 9, in a second part of the process, the side 18C isretained within the mold 50 with the marginal spaces 42, 44, 46, 48(FIG. 2) seated upon the surface 62. Since the displacement between thesurfaces 58, 62 is one third of the width 14, two thirds of the edge 12extends from the mold 50. It should be understood that during the secondpart of the process, the two thirds of the edge 12 that extends from themold 50 includes one third of the edge 12 that did not extend from themold 50 during the first part of the process.

The frame 64 frames a second high impact polystyrene sheet 94, similarto the sheet 67. The frame 64 with the sheet 94 is fixedly positionedabove the mold 50. The heater 68 is positioned proximal to the fame 64.

As shown in FIG. 10, the heater 68 is used to heat the sheet 94 and theframe 64 mold 50 is moved in a direction of the arrows 63 in a mannersimilar to that described in connection with the first part of theprocess.

As shown in FIG. 11, the mold 50 is moved until a portion of the sheet94 that covers the surface 80 (FIG. 5B) is seated upon the surface 58.Because of the holes 90 (FIG. 8), when the vacuum pump 84 operates, airmay pass to the pump 84. However, the sheet 94 is not porous, therebycausing one atmosphere of air pressure to draw the sheet 94 onto the topside 16. Since the sheet 94 is connected to the frame 64 as describedhereinbefore, all portions of the core 10 that extend above the mold 50contact the sheet 94.

In accordance with the second part of the process, the expandedpolystyrene proximal to the portions of the surface of core 10 thatextends from the mold 50 chemically combines with the high impactpolystyrene of the sheet 94 to form the strengthened polystyrene.Moreover, because the displacement between the surfaces 58, 62 is lessthan one half of the width 14, the strengthened polystyrene is formedproximal to the entire edge 12.

The dunnage platform formed by the process weighs approximately eightpounds and can carry an approximately 3500 pound load.

As shown in FIG. 8 the legs 20C-22C, the legs 23C-25C and the legs26C-28C are arranged in parallel columns 95-97, respectively. Thecolumns 95-97 are spaced so that tines of a fork lift can fit betweenthe columns 95, 96 and between the columns 96, 97. Accordingly, with thetines parallel to the columns 95-97, the fork lift can lift the dunnageplatform from either of two sides.

Similarly, the legs 20C, 23C, 26C, and the legs 21C, 24C, 27C and thelegs 22C, 25C, 28C are arranged in parallel rows 98-100, respectively,that are orthogonal to the columns 95-97. The rows 98-100 are spaced sothat tines of a fork lift can fit between the rows 98, 99 and betweenthe rows 99, 100. Accordingly, with the tines parallel to the columns98-100, the fork lift can lift the dunnage platform from either of twosides.

While the invention has been particularly shown and described withreference to a preferred embodiment, it should be understood by thoseskilled in the art that changes in form and detail may be made thereinwithout departing from the spirit and scope of the invention.

1. A process for making a load bearing structure, comprising the stepsof: inserting an expanded polymer core into a forming mold; heating afirst high impact polymer sheet; combining a first side and at leasthalf the thickness of the expanded polymer core extending from theforming mold with the first high impact polymer sheet, where the formingmold comprises an interior complimentary to the shape of the expandedpolymer core; removing the polymer core from the mold; re-inserting theexpanded polymer core into a forming mold, where a second side and aportion of the expanded polymer core extend from the forming mold;heating a second high impact polymer sheet; and substantiallysurrounding the second side of the expanded polymer core and at leastthe portion of the expanded polymer core extending from the forming moldwith the second high impact polymer sheet.
 2. The process of claim 1,where the forming mold has rectangularly disposed walls.
 3. The processof claim 1, where the first high impact polymer sheet contacts thesecond high impact polymer sheet along a portion of the thickness of thepolymer core.
 4. The process of claim 1, where a frame is used to holdone or both the first high impact polymer sheet and the second highimpact polymer sheet prior to combining with the polymer core.
 5. Theprocess of claim 1, further comprising means for holding one or both theframe and the edges of the first high impact polymer sheet fixed.
 6. Theprocess of claim 1, further comprising means for holding one or both theframe and the edges of the second high impact polymer sheet fixed. 7.The process of claim 1, where at least one of the first and the secondhigh impact polymer sheets is chemically combined with one or both thefirst side and the second side of the polymer core.
 8. The process ofclaim 1, where the load bearing structure is a dunnage platform.
 9. Aprocess for making a load bearing structure, comprising: providing aforming mold having an interior complementary to a shape outlined by anedge of an expanded polymer core; retaining in the forming mold theexpanded polymer core, where a first side and at least half of the edgeof the expanded core extend from the forming mold; heating a first highimpact polymer sheet to a temperature; moving the expanded polymer coreinto contact with the heated first high impact polymer sheet to combinethe first side and at least half of the edge of the expanded polymercore with the first high impact polymer sheet; retaining into a formingmold the expanded polymer core, where a second side and at least half ofthe edge of the expanded polymer core extend from the forming mold;heating a second high impact polymer sheet to a temperature; and movingthe second side and at least the portion of the expanded polymer coreextending from the forming mold into contact with the heated second highimpact polymer sheet, where the second high impact polymer sheetcontacts the first high impact polymer sheet on the edge.
 10. Theprocess of claim 9, where the expanded core has a plurality of legsextending therefrom and the process includes covering the plurality oflegs with one of the first high impact polymer sheet and the second highimpact polymer sheet.
 11. The process of claim 9, where one or both thefirst high impact polymer sheet and the second high impact polymer sheetare heated to a temperature in a range of between: 293° F.; and 375° F.12. The process of claim 9, where the load bearing structure is adunnage platform.
 13. A process for making a load bearing structure,comprising the steps of: inserting an expanded polymer core into aforming mold; heating a first high impact polymer sheet; combining afirst side and at least half the thickness of the expanded polymer coreextending from the forming mold with the first high impact polymersheet; removing the polymer core from the mold; re-inserting theexpanded polymer core into a forming mold, where a second side and aportion of the expanded polymer core extend from the forming mold, wherethe forming mold comprises an interior complimentary to the shape of theexpanded polymer core; heating a second high impact polymer sheet; andsubstantially surrounding the second side of the expanded polymer coreand at least the portion of the expanded polymer core extending from theforming mold with the second high impact polymer sheet.
 14. The processof claim 13, where the forming mold has rectangularly disposed walls.15. The process of claim 13, where the first high impact polymer sheetcontacts the second high impact polymer sheet along a portion of thethickness of the polymer core.
 16. The process of claim 13, where aframe is used to hold one or both the first high impact polymer sheetand the second high impact polymer sheet prior to combining with thepolymer core.
 17. The process of claim 13, further comprising means forholding one or both the frame and the edges of the first high impactpolymer sheet fixed.
 18. The process of claim 13, further comprisingmeans for holding one or both the frame and the edges of the second highimpact polymer sheet fixed.